Microwave ovens convert electrical energy into microwave energy using a component called a magnetron. The energy travels through a channel called a waveguide into the oven cavity. The microwaves are produced at a frequency of 2,450 megahertz and vibrate water molecules in food, generating heat. This operating principle distinguishes microwave ovens from conventional ovens: heat is produced by the movement of molecules within the food rather than from its surface. As a result, microwave cooking often takes less time than cooking in a conventional oven or on a stovetop.
What Kind of Energy Do Microwaves Carry?
Microwaves are nonionizing electromagnetic waves. This type of wave is not powerful enough to change the structure of matter or living cells. Gamma rays and X-rays are ionizing waves that can alter cell structure and are subject to strict rules. A microwave oven converts electrical energy to microwave energy and then to heat. Food is heated by thermal energy, and microwaves do not leave a lasting effect in food. Microwave production stops as soon as the oven is turned off.
What to Keep in Mind When Using a Microwave Oven
Check the door seal regularly. Do not use a microwave oven if its door is worn, punctured, or damaged, since damage may affect how energy is distributed. Keep the door fully closed while the oven is running for efficient heating and safe use. Clean the interior regularly and make sure the turntable can rotate freely. Do not put metal containers or gold-trimmed dishes in the oven; metal can reflect microwaves and cause sparking.
Which Foods Should Not Be Heated in a Microwave?
Foods containing milk or dairy can heat unevenly and boil over, so heating them at low power in short intervals is recommended. Sealed foods such as eggs in their shells should not be microwaved because steam pressure can build up inside and cause them to burst. When large pieces of frozen meat are defrosted in a microwave, the outside may begin to cook while the center remains frozen, making safe heating more difficult. For that reason, cook meat thawed in the microwave immediately, without holding it. Loosen the lid on covered dishes slightly so steam can escape and help prevent boilovers.
Microwave vs. Conventional Oven
Conventional ovens heat food from the outside inward, while microwave ovens heat it by moving water molecules within the food. Microwave-cooked food does not brown or form a crust. For browning, use the microwave's broil function or a conventional oven. A microwave's main advantages are speed and energy savings: small portions heat much faster than in a conventional oven. Larger or thicker foods may not heat evenly at the center, so a microwave alone may not be sufficient.
When to Use a Microwave Oven
Microwaves are useful for steaming vegetables, thawing frozen foods, and quickly reheating leftovers. Steaming vegetables in a covered container with a small amount of water may also limit some vitamin loss. A microwave is a faster option than a stovetop or conventional oven when heating a small amount of food. Large portions or dishes that need browning may not turn out as expected in a microwave, so use a conventional oven or stovetop for those. Adjust the microwave's power and cooking time to the amount of food to save energy and help prevent uneven cooking.